Integrated circuits (IC) chips are tested before they are packaged in an electronic product, such as a computer. Testing is essential to determine whether the integrated circuit's electrical characteristics conform to the specifications to which it was designed to ensure that electronic product performs the function for which it was designed.
Testing is an expensive part of the fabrication process for a contemporary computing systems. The functionality of every I/O of a contemporary integrated circuit must be tested since a failure to achieve the design specification at even a single I/O can render an integrated circuit unusable for a specific application. Testing is commonly done both at room temperature and at elevated temperatures to test functionality and at elevated temperatures with forced voltages and currents to burn the chips in and to test the reliability of the integrated circuit and to screen out early failures.
Contemporary probes for integrated circuit testing are expensive to fabricate and are easily damaged. In Beaman et al. U.S. Pat. No. 5,635,846, entitled "Test Probe Having Elongated Conductor Embedded in an Elastomeric Material Which is Mounted on a Space Transformer" (which patent is hereby incorporated by reference), a contemporary test probe head is fabricated of a group of elongated metal wire conductors that are attached to a support substrate and then embedded in a potting compound. The wire conductors can be easily damaged with large displacements. In a typical failure, a wire at the probe head breaks off from the substrate at the point of attachment to a pad on the support substrate. Generally, upon such a failure, the entire probe head has to be replaced. Because of the large number of wire conductors in the test probe head, such breakage is not uncommon so that probe head replacement adds substantial expense to the testing of integrated circuits.
Therefore, it is an object of the present invention to provide an improved high density test probe and method of fabrication.
It is another object of the present invention to provide an improved test probe for testing and burning-in of integrated circuits.
It is another object of the present invention to provide an improved test probe and apparatus for testing integrated circuits in wafer form.
It is an additional object of the present invention to provide probes having contacts capable of large displacements which can be used for high performance, functional testing and for high temperature bum-in applications.
It is yet another object of the present invention to provide probe heads that can be reworked several times by replacing individual wires used in the probe.